The invention relates to a printer for printing on individual printing media according to the preamble of claim 1. It is based on WO-A-96/01742.
A printer of the type mentioned is marketed under the designation xe2x80x9cHighPrint 4905xe2x80x9d by Siemens Nixdorf Informationssysteme AG, Paderborn, Germany.
In such a printer, various functions for handling and processing the individual printing medium have to be controlled. Although these functions proceed in a specific sequence, they do not have to be activated in the case of all individual printing media. For example, when processing savings books, functions are activated which are not needed when printing on receipts.
In WO-A-96/01742, it has already been proposed to mount a control shaft such that it can rotate in a printer frame, said shaft being capable of being driven by a motor that can be activated by a printer control system and bearing a control curve which controls at least the activation of the transport device, the activation of the alignment means and the adjustment of the printing-medium stop.
The invention is based on the object of designing a printer of the type mentioned at the beginning in such a way that the individual units for handling a printing medium in the printer can also be operated reliably and in a straightforward manner without hampering one another.
According to the invention, in a printer of the type mentioned at the beginning this object is achieved by the features specified in the characterizing part of claim 1.
Using the control shaft provided in accordance with the invention, it is possible to ensure in a straightforward way that a printing medium inserted into the printer is firstly aligned against the printing-medium stop and brought into a starting position which is suitable for the printing operation, before the transport device is set into operation. By means of the arrangement of the control cams on the control shaft relative to one another, the desired trouble-free progress of the functions is ensured.
The transport device can be controlled in a straightforward way by its comprising at least one driven transport shaft bearing transport rollers and pressure rollers which are associated with the transport rollers and can be adjusted between a pressure or activation position close to the transport rollers and a rest or deactivation position away from the transport rollers. In this case, the motor driving the transport shaft does not need to be switched, so that a control system for controlling the starting and braking of the motor can be dispensed with.
According to a further function, provision is made for the printing bar to be adjustable in relation to the printing head by a control cam on the control shaft between a printing position close to said printing head and a rest position away from the latter, and by the controlled curve of the printing-bar control cam being designed such that the rest position of the printing bar is located in the activation zone of the transport device. On the other hand, that angular range of the control curve of the printing-bar control cam which corresponds to the printing position of the printing bar extends over the deactivation zone and preferably an adjacent part of the activation zone of the transport device.
In order to press the printing medium against the printing bar and therefore to permit clean printing, there is arranged parallel to the printing bar a protective film strip on a film carrier, which can be adjusted between a position close to the printing bar and a position away from the printing bar. According to the invention, in this case the adjustment of the film carrier can be controlled by a film carrier control cam on the control shaft, whose control curve is designed such that there is correspondence between the printing position of the printing bar and the position of the film carrier close to the printing bar, on the one hand, and the rest position of the printing bar and the position of the film carrier away from the printing bar, on the other hand. In the rest position of the printing bar, the receipt can therefore be transported into the printer without hindrance while it is pressed against the printing bar by the film strip in the printing position of the printing bar, and is therefore held in a position ensuring clean printing.
In the case of specific printing media, it is necessary to obtain information about the type of printing medium before the printing operation. For this purpose, the printer has a reading device which, for example, is designed for reading characters produced on the printing medium with magnetic ink, and has at least one magnetic head and a first printing-medium pressure device which, according to the invention, can be activated by a control cam on the control shaft, the control curve of this control cam being designed such that the activation zone of the first printing-medium pressure device is located in the zone corresponding to the rest position of the printing bar.
Furthermore, in the printer there can be provided a reading/writing device for reading and writing on a magnetic strip on a printing medium, which has a magnetic head arrangement and a second printing-medium pressure device. According to the invention, this can likewise be activated by a control cam on the control shaft, the control curve of this control cam being designed such that the activation zone of the second printing-medium pressure device is located within the activation zone of the first printing-medium pressure device.
It is expedient for the start position and end position of the control shaft, between which the latter can be rotated to and fro, to be defined by a switching flag arranged on the control shaft.